By default, each rental is its own activity, and the material participation tests are applied to each one separately. Three properties with 70, 50 and 40 hours are three failures of the 100-hour test, not one success with 160. The regulations allow certain activities to be grouped into a single activity, which changes the arithmetic, but grouping is an election made on the return with its own consequences. The log has to be built so that either answer can be produced from it.
The default: activity by activity
Section 469 operates on "activities," and Treas. Reg. §1.469-4 explains how to decide what an activity is. Absent a grouping, each property you own is generally treated on its own. You apply the tests in Treas. Reg. §1.469-5T to that property's hours: more than 100 hours and more than anyone else, or more than 500 hours, or substantially all of the participation in it.
This surprises owners who think in portfolio terms. You spent 160 hours "on the rentals" — but if an examiner asks which property each hour belonged to and the log cannot say, the hours may not be usable for any of them.
What grouping does
Treas. Reg. §1.469-4 permits grouping two or more activities into a single activity if they form an appropriate economic unit. The regulation lists factors: similarities and differences in the types of activities, common control, common ownership, geographic location, and interdependencies. Grouped activities are then tested together, so participation across the group counts toward one set of hours.
Three things to know before you start planning around it:
- It is an election, made with the return. It is not something you decide in December by adding up spreadsheets. Your preparer makes it, in writing, following the procedure in the regulations and the relevant revenue procedure.
- It is sticky. Once made, a grouping generally must be used consistently in later years, and regrouping is allowed only in limited circumstances. A choice that helps this year can bind you in a year when it does not.
- It is not the same as the real estate professional aggregation election. The §469(c)(7)(A) election to treat all rental real estate as one activity is a different election, for a different purpose. The 750-hour test guide covers that side.
Because both the availability and the wisdom of a grouping depend on facts we cannot see, this is a question to put to your CPA with your log in hand, not a lever to pull yourself.
The seven-day test stays per property
Here is the part owners miss. Grouping affects how participation is measured. It does not merge the average-period-of-customer-use test in Treas. Reg. §1.469-1T(e)(3)(ii)(A), which is computed from the actual stays at a property. A cabin averaging four nights and a condo averaging nineteen do not average into an eleven-night portfolio for that purpose; each property has its own stay pattern, and the exception applies where it applies.
So a portfolio can easily land in a mixed position: one property outside the rental definition and one inside it, even under a single grouping for participation purposes. Track stays per property regardless of what you do with hours.
How to log so both answers are available
The logging rule is simple and it costs nothing: tag every entry with the property. Never write an entry that says only "rentals." If an hour genuinely covered two properties — a supply run for both, a call with the insurance broker about the portfolio — split it by a reasonable method and say in the entry how you split it.
With per-property tags in place, any total can be produced on demand:
| Question | Answer from the same log |
|---|---|
| Did I pass 100 hours on the cabin? | Filter property = cabin |
| Did anyone participate more than me on the cabin? | Cabin hours vs cabin's other participants |
| If we group, what is the combined total? | Sum across the grouped properties |
| What was the cabin's average stay? | Stay count and nights for the cabin |
STR Tracker keeps each property's log separate with its own running total, and totals across properties when you want the combined view, which is what makes both conversations possible in February. A spreadsheet does the same thing as long as the property column is never blank.
A worked example
Three short-term rentals, all self-managed, cleaners hired at each:
- Cabin: you 70 hours, cleaner 55 hours
- Condo: you 50 hours, cleaner 60 hours
- Cottage: you 40 hours, cleaner 20 hours
Tested separately, none of the three passes the 100-hour test. The cabin and cottage fail on the number; the condo fails on both the number and the comparison, since the cleaner did more.
If the three were properly grouped as one activity, the combined participation would be 160 hours against a combined 135 for the cleaners — which clears 100 and clears the comparison, assuming the cleaners are individuals whose hours are counted this way and no one else participated more. Whether that grouping is available and appropriate is exactly the question for your CPA, and it turns on the economic-unit factors, not on the fact that it produces a better answer.
Notice how much the conclusion depends on the other participants' numbers. If you have not been recording your cleaner's hours, neither version of this analysis can be done. The 100-hour test guide covers the comparison prong in detail.
Questions to bring to your CPA before filing
- Are my properties an appropriate economic unit under Treas. Reg. §1.469-4, on these facts?
- If we group, what are the consequences in a year when one property is sold, or when one has income rather than a loss?
- Have I already established a grouping in a prior year that I am bound by?
- Does the grouping interact with the real estate professional aggregation election, if I am considering that too?
- Given my hours and my cleaners' hours, does grouping actually change the outcome, or am I short either way?
Bring one file per property, dated, with other participants' hours shown. The CPA package guide lists what that looks like. If your log cannot answer question 5 in five minutes, fix the log first — that is the input every other answer depends on, and it is the one thing you control.